1. Field of the Invention
The present invention relates to a solid state light source, and more particularly, to a light source using an array of light emitting diodes elements (LED elements) arranged in a sealed housing.
2. Brief Description of the Prior Art
Specialized light sources have been developed in numerous industries. For example, light sources utilizing fiber optic bundles have been used by machine vision engineers for years to put light just where it is needed. Fiber enables the engineer the generate the precise lighting geometries required to perform difficult inspections. Halogen sources have been a mainstay to illuminate these fiber optic bundles. However, the typical halogen source suffers several shortcomings and was not designed for use on the factory floor. The light from a fresh halogen lamp is brilliant; but, output declines steadily over the lamp's relatively short 1000 hour life. In addition, a typical halogen lamp consumes 150 watts of power and generates a tremendous amount of heat. Consequently, the typical source is not a sealed, shock resistant unit because ventilation is required. Due to these design considerations, present product offerings are housed in heavy, bulky enclosures.
In addition to use as a light source for the purpose of illumination, LED elements are also commonly used for information display such as LED element display panels, “power on” indicators and the like. Within the meaning of this application, a light source is a lighting device used for illumination. An LED element used for the purpose of information display will typically be on the order of less than one hundred (<100) milli-candela whereas an LED element used for illumination will typically be on the order of at least one thousand (≧1000) milli-candela. Consequently, there is a large distinction in the industry between LED based light sources and LED based display devices.
Advances in LED technology have prompted a number of well-known manufacturers in the machine inspection industry to introduce products to eliminate not only the halogen source but the fiber optic bundle as well. Lines, rings, and panels which were once strictly the domain of fiber optics are now being populated with LED elements. Other speciality units such as on-axis and cloudy day illuminators are also available in LED form. At first glance, this appears to be a technically sound, cost-effective illumination alternative. While not as bright, LED technology offers features and capabilities unavailable with halogens. However, the illumination patterns generated from these products are generally poor and uneven because the individual LED elements produce hot spots that randomized fiber optic would have eliminated.
Northeast Robotics, Fostec, Illumination Technologies, & Dolan Jenner are representative of the companies in the machine vision illumination industry. Northeast Robotics is the assignee of U.S. Pat. Nos. 6,177,954; 6,135,350; 6,059,421; 6,003,992; 5,949,584; 5,920,643; 5,877,899; 5,842,060; 5,764,874; 5,761,540; 5,713,661; 5,684,530; 5,604,550; 5,461,417; and 5,187,611. Fostec is the assignee of U.S. Pat. Nos. 5,887,102 and 5,187,765. Illumination Technologies is the assignee of U.S. Pat. Nos. 5,752,767; 5,661,838; 5,591,972; 5,550,946. Dolan Jenner is the assignee of U.S. Pat. Nos. 5,997,164; 5,820,250; 5,790,734; 5,579,177; 5,276,504; RE34,345; 5,229,842; 5,102,227; 4,772,128; and 4,280,122.
There still remains a need in the machine vision industry for a durable, low cost, low power, light source providing effective lighting to the desired location. This need is not limited to the machine vision industry. Durable, low cost, low power, light source providing effective lighting to the desired location would also be particularly well-suited for portable light sources such as flashlights, bicycle lights, helmet lights; hand-held lanterns and the like. Regarding flashlights and the like, Mag Instruments is the assignee of U.S. Pat. Nos. D336,535; D335,718; 5,193,898; 5,184,884; and 5,062,026. The Brinkmann Corp. is the assignee of U.S. Pat. Nos. D445,926; D436,200; D414,887; and D413,401. Ledtronics is the assignee of U.S. Pat. Nos. D434,510; D405,201; D404,506; and D402,772. In a similar fashion, a durable, low cost, low power, light source providing effective lighting to the desired location would also be well-suited for other specific lighting areas such as outdoor lighting, back-up or emergency lighting, interior vehicle lighting and numerous other applications. LED light sources have been proposed in a number of areas, but have not yet adequately addressed all of the lighting criteria. See for example U.S. Pat. No. 6,290,382 (LED vision system); U.S. Pat. No. 6,283,613 (LED traffic light); U.S. Pat. No. 6,276,822 (LED headlight); U.S. Pat. No. 6,268,702 (LED warning light); U.S. Pat. No. 6,234,645 (LED white light); U.S. Pat. No. 6,220,722 (LED white light for aeroplane cabin); U.S. Pat. No. 6,220,719 (LED flashlight); U.S. Pat. No. 6,168,288 (LED flashlight); U.S. Pat. No. 6,095,661 (LED flashlight); U.S. Pat. No. 6,639,716 (LED light); U.S. Pat. No. 6,028,694 (LED light); U.S. Pat. No. 5,897,195 (LED light); U.S. Pat. No. 5,850,126 (LED light); U.S. Pat. No. 5,634,711 (LED light); U.S. Pat. No. 4,234,911 (LED flashlight); U.S. Pat. No. 4,211,955 (LED light).
It is an object of the present invention to provide a durable, low cost, low power, light source providing effective lighting to the desired location for a variety of specific applications. It is another object of the present invention to provide such durable, low cost, low power, light source providing effective lighting to the desired location effective for the machine vision illumination and usable as a fiber optic bundle lighting source. It is another object of the present invention to provide a light source that is economically manufactured and easily usable with a variety of applications.